The reason we don't notice smaller objects, like people or chairs, pulling on each other through gravity has to do with the relative strength of the gravitational forces involved and the effects of mass.
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Gravitational Force: The gravitational force between two objects is determined by Newton's law of gravitation, which states that the force (\(F\)) between two masses (\(m_1\) and \(m_2\)) is proportional to the product of their masses and inversely proportional to the square of the distance between their centers:
\[ F = G \frac{m_1 m_2}{r^2} \]
Here, \(G\) is the gravitational constant. The force is very small for objects that have relatively low mass compared to, for example, the mass of the Earth.
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Massive Earth: The Earth is extremely massive (about \(5.97 \times 10^{24}\) kilograms), which means the gravitational force it exerts on us and other objects is significantly stronger than the forces that we exert on each other. A person's gravitational force on you is negligible compared to the Earth's pull on you.
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Relative Scale: The gravitational attraction between two smaller objects is minuscule. For example, the gravitational force between two people is incredibly small when compared to the gravitational force they each experience from the Earth. This is why we don't notice their pull on each other.
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Perceived Weight: What we experience as weight is actually the result of the Earth's gravity pulling us down. Other gravitational forces around us (like those from nearby people or furniture) are too weak to have any noticeable effect on our sensation of weight or movement.
In summary, while all objects do exert gravitational forces on each other, the forces between smaller objects are so minor compared to the gravitational force from the Earth that they go unnoticed in our everyday experiences.